This article is about the load UDB event handler.
load
The load event may be called from web pages developed in Web Designer and processed by a USoft page engine service.
| Event | Applies to | Occurs when |
|---|---|---|
| Page objects | The first time the page is constructed |
This event is similar, but not identical, to the HTML onload event.
The HTML onload event :
- Is usually attached to the <body> DOM element.
- Occurs when the document has finished loading.
- For images, this event occurs when the specific image has finished loading and is displayed on the screen.
- For scripts, this event occurs when the script file content has been loaded. The script itself has NOT been executed at this time; script execution happens in parallel to anything defined for the event, but independently of it.
The USoft load event is different, because USoft uses dynamic page construction. This event:
- Is usually attached to the top-level Page object.
- Occurs at the time when all data sources have been created and initiated * and all USoft UI controls and their child elements have been created **.
* At the time when a data source is created and initiated, the query has started, but has not necessarily completed. When load occurs, any 'deferred query' data sources have not started yet: if they contain asynchronous content, they are started immediately after the event handling is started; otherwise, they are started when event handling has finished.
** At the time when USoft UI controls are created, they have all been added to the DOM as well.
How to use
Find or create an Event Listener object with Event Type = load. Event Listeners are in the Web Designer Controls catalog:
Insert the event listener into the Page object. Insert a callClientScript action into the event listener. Use this action's Script property to code the behaviour that you want to see when the event occurs.
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